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M. Gende , C. Brunini Universidad Nacional de La Plata, Argentina.

Improving Single Frequency Positioning Using SIRGAS Ionospheric Products. M. Gende , C. Brunini Universidad Nacional de La Plata, Argentina. Outlook. Goal and motivations Why in South America? Workflow Results for a test bed Conclusions. Goal.

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M. Gende , C. Brunini Universidad Nacional de La Plata, Argentina.

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  1. Improving Single Frequency Positioning Using SIRGAS Ionospheric Products M. Gende, C. Brunini Universidad Nacional de La Plata, Argentina.

  2. Outlook • Goal and motivations • Why in South America? • Workflow • Results for a test bed • Conclusions IAG Scientific Assembly: Geodesy For Planet Earth.

  3. Goal • Increase precise positioning accuracy for single frequency receivers. IAG Scientific Assembly: Geodesy For Planet Earth.

  4. Motivation • A large part of the GNSS technology users in Latin American have access only to single frequency receivers. • These receivers can not eliminate the ionospheric bias by combining signals. IAG Scientific Assembly: Geodesy For Planet Earth.

  5. Basic Facts • The ionosphere delay is the main error factor in positioning. • This delay can be mitigated with a differencing technique. • The technique lose effectiveness as the baseline increases. IAG Scientific Assembly: Geodesy For Planet Earth.

  6. Context in South America • Because of the size of the continent,the GNSS continuously operating reference stations (CORS) are usually more than 300 kilometers from each other. • Under this condition the relative positioning method is less effective. IAG Scientific Assembly: Geodesy For Planet Earth.

  7. IAG Scientific Assembly: Geodesy For Planet Earth.

  8. Our proposal • Use the CORS network already installed in order to produce ionospheric corrections for single frequency receivers. IAG Scientific Assembly: Geodesy For Planet Earth.

  9. Methodology • Determine the slant total electron content (STEC) from dual frequency CORS. • Estimate STEC in the place the user is located. • Correct the single frequency observations. • Process the observations in a regular way. IAG Scientific Assembly: Geodesy For Planet Earth.

  10. 1st step: calculate STEC using LPIM • Absolute STEC must be determined. • Receiver calibration • The estimation is done at the zero difference level • We assume a thin shell model. IAG Scientific Assembly: Geodesy For Planet Earth.

  11. 2nd step: Estimate STEC • Estimate STEC • For each receiver – satellite observation • For each epoch IAG Scientific Assembly: Geodesy For Planet Earth.

  12. 3rd step: Correct the observations • We can correct measurements • Corrected C/A and Corrected L1 • We can generate new measurements • Simulated P2 and Simulated L2 • The user has a new RINEX file with less ionospheric bias IAG Scientific Assembly: Geodesy For Planet Earth.

  13. 4rd step: Conventional processing • Positioning is performed using the software that the user usually uses. • We have extended the CORS – user’s distance. IAG Scientific Assembly: Geodesy For Planet Earth.

  14. Evaluation • In the position domain • Code and phase • Static and cinematic • Comparison • Single frequency solution • Corrected solution • Ion free solution IAG Scientific Assembly: Geodesy For Planet Earth.

  15. Test bed • 10 days, 24 hours. • Mid latitude. • Non disturbed solar conditions. • Distance between GPS receivers 200 to 300 Km. IAG Scientific Assembly: Geodesy For Planet Earth.

  16. IAG Scientific Assembly: Geodesy For Planet Earth.

  17. Standalone positioning

  18. Horizontalcoordinates Delta North (meters) C/A code C/A code + corrections Ion-free Delta East (meters) IAG Scientific Assembly: Geodesy For Planet Earth.

  19. Vertical component Delta Up (meters) Local Time (hours) P1 Simulated ion-freeIon-free IAG Scientific Assembly: Geodesy For Planet Earth.

  20. Differential positioning using code

  21. Horizontalcoordinates C/A C/A + corrections C/A code C/A code + corrections Delta North (meters) Delta East (meters) IAG Scientific Assembly: Geodesy For Planet Earth.

  22. Vertical component Delta Up (meters) Local Time (hours) C/A C/A corrected IAG Scientific Assembly: Geodesy For Planet Earth.

  23. Differential positioning using carrier phase

  24. Delta East (meters) Horizontalcoordinates Delta North (meters) C/A C/A C/A + corrections Local Time (hours) C/A + corrections IAG Scientific Assembly: Geodesy For Planet Earth.

  25. Vertical component C/A Local Time (hours) C/A + corrections IAG Scientific Assembly: Geodesy For Planet Earth.

  26. Conclusions • It is possible to: • Mitigate the ionospheric effect on L1. • Extend the separation between the user and a CORS station. • When corrections are applied: • The horizontal errors are reduced more than 40%. • The vertical errors are reduced almost 60%. • 95% of the time the corrected observations present errors below. • 1 centimeter for the horizontal coordinates. • 10 centimeters for the height. IAG Scientific Assembly: Geodesy For Planet Earth.

  27. Extended utility IAG Scientific Assembly: Geodesy For Planet Earth.

  28. IAG Scientific Assembly: Geodesy For Planet Earth.

  29. IAG Scientific Assembly: Geodesy For Planet Earth.

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